As disclosed in Examined Published Japanese Utility Model Application Nos. 61-33970, 61-33971 and 61-33973 and U.S. Pat. No. 4,438,931 corresponding thereto, there has conventionally existed such type of metal wood that comprises a golf club head formed of a plurality of metallic shell pieces integrally welded together and a metallic face member welded thereto. Further, as disclosed in Unexamined Published Japanese Patent Application Nos. 5-137818 and 6-142236 and U.S. Pat. No. 5,429,357 corresponding thereto, there has been proposed such type of golf club that has a head having a front opening to which a face member made of a metallic plate is welded.
For manufacturing a golf club head comprising a plurality of metallic shell pieces integrally welded together, it has been usual that as disclosed in U.S. Pat. No. 5,232,224, the shell pieces are welded while they are fixed to a predetermined jig and in order to fix a shaft to such golf club head accurately, a shaft-mounting pipe fixed to a predetermined jig is welded to the golf club head while the fixing angle of the shaft-mounting pipe is adjusted.
In the case of the above-described conventional technology, where the shaft-mounting pipe for mounting a shaft to the golf club head is fixed to the golf club head, since the loft angle and the lie angle must be determined, a specific jig is required for the sake of accuracy of fixation and every time when the shaft-mounting pipe is welded to the golf club head, the fixing angle must be adjusted.
Moreover, it has been practiced that in view of the easiness of molding and weldability of the golf club head and the balancing of the center of gravity thereof, the thickness of the shell piece at the sole portion of the head is made thicker than the crown portion and pure titanium is used as a material for the golf club head. Accordingly, the conventional technology has had the disadvantage that the rigidity of the golf club head as a whole is not strong and when attempting to increase its rigidity, the thickness of each of the shell pieces for forming the head is forced to be made large which results in losing a favorable weight balance.